package com.zhiliao.component.spring;

import org.apache.commons.lang3.Validate;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.BeansException;
import org.springframework.beans.factory.DisposableBean;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import org.springframework.context.annotation.Lazy;
import org.springframework.stereotype.Component;

import java.util.Map;

/**
 * Description:
 *
 * @author qirong
 * @date 2018-10-26
 */
@Component
@Lazy(false)
public class SpringContextHolder  implements ApplicationContextAware, DisposableBean {

	private static Logger log = LoggerFactory.getLogger(SpringContextHolder.class);

	private static ApplicationContext applicationContext = null;

	/**
	 * 从静态变量applicationContext中取得Bean, 自动转型为所赋值对象的类型
	 * @param name
	 * @param <T>
	 * @return
	 */
	public static <T> T getBean(String name) {
		assertContextInjected();
		return (T) applicationContext.getBean(name);
	}

	/**
	 * 从静态变量applicationContext中取得Bean, 自动转型为所赋值对象的类型
	 * @param requiredType
	 * @param <T>
	 * @return
	 */
	public static <T> T getBean(Class<T> requiredType) {
		assertContextInjected();
		return applicationContext.getBean(requiredType);
	}

	public static <T> Map<String, T> getBeansOfType(Class<T> requiredType) {
		assertContextInjected();
		return applicationContext.getBeansOfType(requiredType);
	}

	/**
	 * 注入Context到静态变量中
	 * @param applicationContext
	 * @throws BeansException
	 */
	@Override
	public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
		log.debug("*************************** [SpringContextHolder Init] ******************************");
		log.debug("注入ApplicationContext到SpringContextHolder:{}", applicationContext);
		if(null != SpringContextHolder.applicationContext) {
			log.debug("SpringContextHolder中的ApplicationContext被覆盖, 原有ApplicationContext为:" + SpringContextHolder.applicationContext);
		}
		SpringContextHolder.applicationContext = applicationContext;
	}

	/**
	 * 实现DisposableBean接口, 在Context关闭时清理静态变量.
	 *
	 * @throws Exception
	 */
	@Override
	public void destroy() throws Exception {
		SpringContextHolder.clearHolder();
	}

	/**
	 * 清除SpringContextHolder中的ApplicationContext为Null
	 */
	public static void clearHolder() {
		if (log.isDebugEnabled()) {
			log.debug("清除SpringContextHolder中的ApplicationContext:" + applicationContext);
		}
		applicationContext = null;
	}

	/**
	 * 检查ApplicationContext不为空
	 */
	private static void assertContextInjected() {
		Validate.validState(applicationContext != null,"applicaitonContext属性未注入！");
	}

	public static ApplicationContext getApplicationContext() {
		return applicationContext;
	}

}
